The American Journal of Tropical Medicine and Hygiene - Volume 91, Issue 6, December 2014

Growing interest in mass vaccination with oral cholera vaccine in endemic and epidemic settings will require policymakers to evaluate how to allocate these vaccines in the most efficient manner. Because cholera, when treated properly, has a low case fatality rate, it may not be economically feasible to vaccinate an entire population. Using a new publicly available calculator for estimating the cost-effectiveness of mass vaccination, we show how targeting high-risk subpopulations for vaccination could be cost-effective in Bangladesh. The approach described here is general enough to adapt to different settings or to other vaccine-preventable diseases.

This study examined the relationship between childhood diarrhea prevalence and caregiver knowledge of the causes and prevention of diarrhea in a prospective cohort of 952 children < 5 years of age in Cochabamba, Bolivia. The survey of caregiver knowledge found that more than 80% of caregivers were unaware that hand washing with soap could prevent childhood diarrhea. Furthermore, when asked how to keep food safe for children to eat only 17% of caregivers reported hand washing before cooking and feeding a child. Lack of caregiver awareness of the importance of practices related to hygiene and sanitation for diarrhea prevention were significant risk factors for diarrheal disease in this cohort. The knowledge findings from this study suggest that health promotion in these communities should put further emphasis on increasing knowledge of how water treatment, hand washing with soap, proper disposal of child feces, and food preparation relate to childhood diarrhea prevention.

We collected for rural western China data for 14,658 children less than 36 months of age in 2001 and for 14,112 children in 2005. A generalized estimated equation log-binomial model was used to identify the determinants of childhood diarrhea. In 2005, prevalence of diarrhea was approximately 7.4%, which compared with that for 2001, had decreased by 8.7%. The generalized estimated equation analysis showed that region affected the prevalence of childhood diarrhea significantly. Age was negatively associated with childhood diarrhea. Although childhood upper respiratory infections increased the risk of diarrhea, the risk could be decreased by use of vitamin A in the previous year. In addition, children of Han ethnicity or those living in one-child families had a lower risk of diarrhea in 2001, but underweight children had a higher risk in 2005. These findings may have some implications for formulating policies of childhood diarrhea prevention and control in rural western China.

Much of the basic clinical information about dengue infection comes from experimental human studies conducted in the 1920s and 1940s. Albert Sabin's original laboratory records from one such study were bequeathed to Duane J. Gubler. These records were reviewed and 150 experiments were included in our analyses. Persons were inoculated with dengue virus 1 (DENV-1) and DENV-2. Median fever duration was shorter in primary DENV-2 infections compared with DENV-1, although maximum temperature and severity of illness were comparable. At 1.5–9 months after primary infection, 20 persons were inoculated with the heterologous serotype. Only one person inoculated with a heterologous serotype at < 8 weeks showed development of a clinical infection with a maximum temperature of 38°C, and 7 (88%) of 8 persons inoculated with a heterologous serotype at 4–9 months post-primary infection showed development of fever. On average, persons had a shorter incubation period in secondary infection compared with primary infection.

Half a million patients are hospitalized with severe dengue every year, many of whom would die without timely, appropriate clinical intervention. The majority of dengue cases are uncomplicated; however, 2–5% progress to severe dengue. Severe dengue cases have been reported with increasing frequency over the last 30 years. To discover biomarkers for severe dengue, we used surface-enhanced laser desorption/ionization time-of-flight mass spectrometry to analyze dengue virus positive serum samples from the acute phase of infection. Using this method, 16 proteins were identified as candidate biomarkers for severe dengue. From these 16 biomarkers, three candidates were selected for confirmation by enzyme-linked immunosorbent assay and Western blot: vitronectin (Vtn, 55.1 kDa), hemopexin (Hx, 52.4 kDa), and serotransferrin (Tf, 79.2 kDa). Vitronectin, Hx, and Tf best differentiated between dengue and severe dengue.

Dengue is the most important mosquito-borne viral disease to humans. Bats are potential reservoirs for flaviviruses, including dengue virus (DENV). In this work, Artibeus jamaicensis bats were inoculated with two serotypes of DENV using different routes. For experimental inoculations (EI) 1 and 2, bats were inoculated subcutaneously or intraperitoneally with DENV-4; for EI-3 bats were inoculated intraperitoneally with DENV-1. Mock inoculated bats were kept as controls. In EI-4, bats were bitten by Aedes aegypti mosquitoes infected with DENV-1 or 4. Reverse transcription-polymerase chain reaction assays in plasma and spleen tissue collected from Day 1 to Days 9–17 after inoculation failed to reveal the presence of viral RNA in any of the samples. No evidence of circulating NS1 or specific anti-DENV IgG was detected in the plasma of the inoculated bats. These results indicate that A. jamaicensis bats are incapable of sustaining dengue virus replication and are unlikely to act as reservoirs for this virus.

Between 2006 and 2012 India reported an annual average of 20,474 dengue cases. Although dengue has been notifiable since 1996, regional comparisons suggest that reported numbers substantially underrepresent the full impact of the disease. Adjustment for underreporting from a case study in Madurai district and an expert Delphi panel yielded an annual average of 5,778,406 clinically diagnosed dengue cases between 2006 and 2012, or 282 times the reported number per year. The total direct annual medical cost was US$548 million. Ambulatory settings treated 67% of cases representing 18% of costs, whereas 33% of cases were hospitalized, comprising 82% of costs. Eighty percent of expenditures went to private facilities. Including non-medical and indirect costs based on other dengue-endemic countries raises the economic cost to $1.11 billion, or $0.88 per capita. The economic and disease burden of dengue in India is substantially more than captured by officially reported cases, and increased control measures merit serious consideration.

Crimean–Congo hemorrhagic fever virus (CCHFV) and dengue virus (DENV) are endemic to Pakistan. Patients presenting with symptoms of fever, bleeding, and rash cannot be distinguished without appropriate testing. We report data on 354 samples tested for CCHFV at The Aga Khan University Hospital in Pakistan between 2007 and 2013. All samples were tested for the presence of CCHFV RNA. Some samples were also tested for DENV RNA, NS-1 antigen, and/or reactive immunoglobulin M antibodies. Of 354 clinical specimens screened for CCHFV, 52 specimens were positive, with 24 cases in 2013 alone. Most cases were from Sindh and Baluchistan, which border other CCHFV-endemic regions: Iran and Afghanistan. Among CCHFV-negative samples, 168 samples were tested for DENV, and 36% of these samples were found to be DENV-positive. Rapid differentiation of CCHFV and DENV can prevent nosocomial transmission and result in time and cost savings for patients and healthcare workers.

Mute swans (Cygnus olor) are an invasive species in the United States. The dramatic increase in their populations in localized areas has led to various problems, among them competition with native species and attacks on humans by aggressive swans. However, very little is known about the ability of these swans to transmit pathogens to humans, domestic birds, or wildlife or participate in enzootic maintenance. To learn more about select pathogens that mute swans may harbor, a survey was conducted from April of 2011 to August of 2012 in the Great Lakes region and localized areas of the Atlantic coast, which revealed serologic evidence of arbovirus exposure in mute swans. Of 497 mute swans tested, antibodies were detected for eastern equine encephalitis (4.8%), St. Louis encephalitis (1.4%), West Nile (1.2%), and Turlock (0.6%) viruses. Samples were also tested for evidence of antibodies to La Crosse virus, but none were positive.

In malaria-endemic regions, many medical facilities have limited capacity to diagnose non-malarial etiologies of acute febrile illness (AFI). As a result, the etiology of AFI is seldom determined, although AFI remains a major cause of morbidity in developing countries. An outbreak of AFI was reported in the Afar region of Ethiopia in August of 2011. Retrospectively, 12,816 suspected AFI cases were identified by review of medical records. Symptoms were mild and self-limiting within 3 days after the date of onset; no fatalities were identified. All initial test results of AFI patient specimens were negative for selected pathogens using standard microbiological and molecular techniques. High-throughput sequencing of nucleic acid extracts of serum specimens from 29 AFI cases identified 17 (59%) of 29 samples as positive for Sandfly Fever Sicilian Virus (SFSV). These results were further confirmed by specific reverse transcription polymerase chain reaction. This is the first study implicating SFSV as an etiological agent for AFI in Ethiopia.

A prospective cohort study of new-onset seizure in people with human immunodeficiency virus (HIV) in Zambia is ongoing to determine the incidence of subsequent epilepsy and risk factors for epileptogenesis in this population. At enrollment, we evaluated this cohort for cognitive impairment and psychiatric morbidity. Over 50% of participants had cognitive impairment and significant psychiatric morbidity. Most participants had advanced HIV disease based on CD4+ T-cell count and World Health Organization stage, but we found no association between cognitive impairment or psychiatric morbidity and HIV disease staging.

Madura foot is a chronic infection caused by fungus and/or bacteria. Traditionally, treatment has been surgical debridement or amputation. Non-invasive management with long-term antimicrobials alone has been reported as successful. We report a case of Madura foot in a Somali refugee successfully managed with oral posaconazole and ciprofloxacin.

We report three cases of lymphocutaneous infection caused by the thermally dimorphic fungus, Sporothrix schenckii from Australia's tropical Northern Territory. Two cases were acquired locally, making them the first to be reported from this region. All three cases presented with ulceration in the limb; however, the classical sporotrichoid spread was present only in the first two cases. Their occurrence within several weeks of each other was suggestive of a common source of environmental contamination such as hay used as garden mulch. Diagnoses were delayed in each case, with each patient having substantial exposure to ineffective antibiotics before the correct diagnosis was made. These cases bring the total number of reported sporotrichosis cases in Australia since 1951 to 199. Lessons from these cases are to consider the diagnosis of sporotrichosis in lesions of typical appearance, even in geographical settings from where this pathogen has not previously been reported.

We have shown that the Centers for Disease Control and Prevention (CDC) autocidal gravid ovitraps (AGO trap) reduced the Aedes aegypti population and prevented mosquito outbreaks in southern Puerto Rico. After showing treatment efficacy for 1 year, we deployed three traps per home in an area that formerly did not have traps and in a site that served as the intervention area. Two new areas were selected as reference sites to compare the density of Ae. aegypti without traps. We monitored mosquitoes and weather every week in all four sites. The hypotheses were the density of Ae. aegypti in the former reference area converges to the low levels observed in the intervention area, and mosquito density in both areas having control traps is lower than in the new reference areas. Mosquito density in the former reference area decreased 79% and mosquito density in the new reference areas was 88% greater than in the intervention areas.

The objective of this study was to describe the screening for imported diseases among an immigrant population. This retrospective observational study was of all adult immigrants attended at the Tropical Medicine Unit of the Vall d'Hebron Teaching Hospital from September of 2007 to March of 2010. The screening strategy was adjusted by symptoms, country of origin, and length of residence in Europe. Overall, 927 patients were included. The median age was 34.5 years, and 42.1% of patients were male. A diagnosis was made in 419 (45.2%) patients. The most frequent diagnoses were Chagas disease, anemia, latent tuberculosis infection, intestinal parasitosis, hepatitis B virus (HBV) infection, and human immunodeficiency virus (HIV) infection. After screening, more diseases were identified in immigrants from sub-Saharan Africa (new diagnoses in 56.6% of patients) than patients from other geographic areas. The geographic origin and length of residence in a developed country determine the prevalence of diseases; hence, screening protocols must be based on this information.